Дисертації з теми "Laser desorption/ laser ionization"

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1

Rogers, Kevin Shaun. "Laser desorption/laser ionization mass spectroscopy." Thesis, University of Salford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357037.

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2

Clipston, Nigel L. "Laser desorption/laser ionization Time-of-Flight Mass Spectrometry." Thesis, University of Salford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360476.

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3

Wen, Xiujuan. "Small Molecule Matrix-free Laser Desorption/ionization Mass Spectrometry." Thesis, The University of Arizona, 2006. http://hdl.handle.net/10150/193332.

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Modified Si wafers and nanoparticles (5-50 nm) have been developed and explored to assist laser desorption ionization mass spectrometry (LDI-MS) for small molecule analysis. DIOS (desorption/ionization on silicon) plates were prepared according to published protocols. DIOS was tested and compared with the optimized silicon nanoparticles derivatized by penterfluorophenylchlorosilane (PFP). SPALDI (Si nanoparticle assisted LDI) requires less laser flux than common MALDI and DIOS thus provides significant less background and higher ionization efficiency. It has higher surface homogeneity, relative salt tolerance and high selectivity which may origin from analyte dependent pre-charging. Surface characterization has been investigated. And different analytes including drugs, peptides, pesticides and acids in both biological and environmental samples have been applied by positive or negative ionization mode. Detection limits, down to the low femtomole per microliter levels have been achieved for propafenone and verapamil. SPALDI is an easily applicable practical tool at a potential low cost.
4

Lu, Tian. "Nanomaterials For Liquid Chromatography and Laser Desorption/Ionization MassSpectrometry." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1376981440.

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5

Peng, Ivory Xingyu. "Electrospray-assisted laser desorption ionization mass spectrometry for proteomic studies." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1997571271&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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6

Berhane, Beniam T. "Rapid Characterization of Posttranscriptional Modifications in RNA Using Matrix Assisted Laser Desorption Ionization Mass Spectrometry and Matrix Assisted Laser Desorption Ionization Post Source Decay Mass Spectrometry." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1052319621.

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7

Dubois, Frédéric Dubois Frédéric. "Ion formation and detection in matrix-assisted laser desorption/ionization mass spectrometry /." [S.l.] : [s.n.], 1999. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13255.

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8

Dai, Yuqin. "Development of matrix-assisted laser desorption ionization mass spectrometry for biopolymer analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0003/NQ39519.pdf.

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9

Shariatgorji, Mohammadreza. "Novel clean-up, concentration and laser desorption/ionization strategies for mass spectrometry /." Stockholm : Department of Analytical Chemistry, Stockholm University, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-32236.

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Diss. (sammanfattning) Stockholm : Stockholms universitet, 2010.
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: In Press. Härtill 7 uppsatser.
10

Tummala, Manorama. "Surfactant-Aided Matrix Assisted Laser Desorption/Ionization Mass Spectrometry (SA-MALDI MS)." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1100672049.

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11

Astorga-Wells, Juan. "Microfluidic electrocapture technology in protein and peptide analysis /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7349-965-x/.

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12

Dashtiev, Maxim. "Fluorescence spectroscopy of trapped molecular ions produced with matrix-assisted laser desorption/ionization /." Zürich : ETH, 2006. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16949.

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13

Zhang, Hui. "Developments and applications of electrophoresis and small molecule laser desorption ionization mass spectrometry." [Ames, Iowa : Iowa State University], 2007.

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14

Segu, Mohideen Mohamed Zaneer. "TARGET MODIFICATION FOR ENHANCED PERFORMANCE MATRIX ASSISTED LASER DESORPTION IONIZATION (MALDI) MASS SPECTROMETRY." Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1674093101&sid=1&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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Thesis (Ph. D.)--Southern Illinois University Carbondale, 2008.
"Department of Chemistry." Keywords: Enhanced MALDI, MALDI-MS, On-probe separation, Protein-surface interactions, Sublayers, Surface binding capacity. Includes bibliographical references (p. 130-148). Also available online.
15

Akinapalli, Srikanth. "MICROFLUIDIC DYNAMIC ISOELECTRIC FOCUSING COUPLED TO MATRIX ASSISTED LASER DESORPTION/IONIZATION MASS SPECTROMETRY." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/dissertations/1289.

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Proteomics is an increasingly important area of biological research and has gathered much attention over recent years. Major challenges that make a proteomic analysis difficult are sample complexity, diversity and dynamic range. Progress in the area of proteomics relies heavily on new analytical tools for the sensitive, selective, and high-throughput studies of target analytes. It is estimated that there are several hundred thousand proteins in a human cell. In order to be able to analyze such a complex sample, an analytical method must be capable of separating and detecting many different sample peaks. The complexity of such samples indicates that a single separation method will not be able to provide the needed resolution. If two methods that are orthogonal are combined, then the peak capacity of the combined system is the product of the two individual peak capacities. Development of such systems would cater to the current demands of proteomics studies. Matrix assisted laser desorption/ionization (MALDI) mass spectrometry has evolved into a primary analytical tool for proteomics research. MALDI is fast and efficient and has a high tolerance to non-volatile buffers and impurities. The samples for MALDI are typically applied to solid supports after having been subjected to off-line liquid or gel separations. Several methods have been reported involving various chromatographic or electrophoretic separation methods. However, the current methods often require highly sophisticated sample handling systems, which are often expensive and in need of skilled human resources. The current demands of proteomic analyses require fast, efficient and inexpensive methods for separation to fully harness the capability of MALDI mass spectrometry. In this work a microfluidic device has been designed to perform dynamic isoelectric focusing (DIEF) based protein separation with digital sample deposition directly on a MALDI target for offline analysis. DIEF is related to capillary isoelectric focusing which and can facilitate the interface without the loss of the separation resolution. Compared to traditional capillary isoelectric focusing (cIEF) DIEF uses additional high-voltage power supplies to control the pH gradient by manipulating the electric field. The proteins can be focused at a desired sampling position according to their isoelectric point, to be collected for further analysis by MALDI mass spectrometry. DIEF has a peak capacity of over a thousand and offers an ease of interfacing to other techniques making it a preferred separation method for the interface with mass spectrometric techniques such as MALDI. The design of the microfluidic device is based on a digital droplet fractionation. Multiple fractions of the sample solution from DIEF are generated to retain the resolution and to act as an additional separation mode. The microfluidic device is controlled by actuating pneumatic valves built into the device. The DIEF operational parameters were optimized according to the surface functionality and the design of the microfluidic device. A suitable MALDI sample preparation method was found by studying different existing methods. The methods were studied using test proteins prepared in solutions having the additives used in the experiment. A simple mixture of three proteins was used to demonstrate the application of the developed method. The separation between the proteins insulin, hemoglobin and the myoglobin was demonstrated by varying the separation resolution in three experiments.
16

Xiang, Fan. "Improvement and investigation of sample preparation for matrix-assisted laser desorption/ionization of proteins." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25780.pdf.

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17

Wang, Jian. "Analyses of food and feed compounds using matrix-assisted laser desorption/ionization mass spectrometry." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0013/NQ59690.pdf.

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18

Liu, Qiang. "Fundamental Study and Method Development for Surface-based Laser Desorption Ionization Imaging Mass Spectrometry." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-02262009-143514/.

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By providing both the chemical identity and the spatial organization of each component in biological samples, Imaging Mass Spectrometry (IMS) becomes an emerging tool in clinic and pharmacological study. Most work in IMS has been focused on protein and peptide mapping in biological samples to take advantage of effective analyte ionization in MALDI-MS, and also partially due to the limitation of MALDI-MS in small molecule detection. The focus of my research is to develop novel tools to image spatial distribution of small molecules in biological samples. A surface-based mass spectrometric imaging method, i.e. Desorption/Ionization on Silicon (DIOS), was used for biological surface analysis in the concept-proof investigation. More over, possible proton transferring pathways and impact of local chemical environment have been systematically investigated in the fundamental understanding of ionization mechanism of SALDI-MS. Based on the finding on the SALDI mechanism, a hybrid ionization approach, ME-SALDI has been developed by combing the strength of the conventional MALDI matrix and SALDI, where the improved detection sensitivity with reduced matrix-analyte interference and the improved imaging capability through analysis of mouse brain and heart sections has been demonstrated. In addition, the impact of vacuum stability of matrix in ME-SALDI-IMS applications has been examined. A solvent free, homogenous and reproducible sublimation method has been developed for ionic matrix in ME-SALDI, by which improved vacuum stability and MS detection have been achieved. Furthermore, a new generation of meso-porous oxide substrate was developed as a novel ME-SALDI substrate with a superior storage stability, extended detectable mass range and robust substrate preparation.
19

Busse, Frederik [Verfasser], and R. J. Dwayne [Akademischer Betreuer] Miller. "Mechanisms of Picosecond Infrared Laser Desorption Ionization / Frederik Busse ; Betreuer: R. J. Dwayne Miller." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2019. http://d-nb.info/1192912977/34.

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20

Mowat, Ian A. "Synthetic polymer analysis using matrix assisted laser desorption/ionization time-of-flight mass spectrometry." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/12128.

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The aim of the work described in this thesis was to assess 'Matrix Assisted Laser Desorption/Ionization' (MALDI) Time-of-Flight mass spectrometry as a possible technique for the analysis of synthetic polymers. A compact home-built time-of-flight mass spectrometer of cylindrically symmetrical geometry was used to carry out all the mass spectrometry detailed described in this thesis. A survey of the literature describing the development of matrix assisted laser desorption/ionization spectrometry and also the previous analysis of polymers by laser mass spectrometry was carried out. Experiments comparing the performance of the apparatus with published data on peptides and proteins were carried out, followed by experiments to assess the possibility of analyzing synthetic polymers. Initially polar polymers were investigated, since they could be anlayzed using sample preparations very similar to those developed for peptide and protein analysis. Later investigations were carried out on non-polar polymers such as polystyrene. The attachment of a range of transition metals to a low mass polystyrene was investigated using laser desorption/ionization time-of-flight mass spectrometry, without the use of matrices to increase the ion yield. Systematic investigations into the effects of sample spot composition, i.e. the amounts of matrix, polymer and salt present, were carried out, and used to suggest possible models for the processes leading to the generations of large gas phase ions. The effects of sample spot composition on the size and shape of the polymer molecular weight distributions obtained was also investigated. Liquid polymers such as polysiloxanes and perfluorinated polyethers were investigated using laser desorption/ionization and matrix assisted laser desorption/ionization. Carbon cluster generation from such polymers was investigated, and fullerene and polycyclic aromatic hydrocarbon analysis was also briefly studied. Novel new molecules such as aryl ester dendrimers were investigated, since they could not be successfully analyzed by other mass spectrometric techniques. Single molecular ions were obtained, helping to confirm the expected masses of these molecules. Novel new polymers such as hyperbranched aromatic polyesters were also analyzed, and molecular weight distributions were successfully obtained for a number of samples, showing the utility of MALDI for the analysis of new materials.
21

Garrett, Timothy J. "Imaging small molecules in tissue by matrix-assisted laser desorption/ionization tandem mass spectrometry." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0013807.

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22

Köchling, Heinrich J. (Heinrich Josef) 1962. "Advancements in matrix-assisted laser desorption ionization mass spectrometry of peptides, proteins and polymers." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/10020.

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23

Priyasantha, Kandalama KD. "DEVELOPMENT OF A NOVEL MATRIX ASSISTED LASER DESORPTION / IONIZATION (MALDI) BASED PEPTIDE QUANTITATION APPROACH." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/dissertations/989.

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Matrix Assisted Laser Desorption / Ionization (MALDI) Mass Spectrometry (MS) has emerged as an important tool in the field of proteomics mainly because it is simple, quick and efficient. The identification and quantitation of biomarkers, protein targets for drugs, and metabolites are some of the important fields in proteomics research. Although MALDI MS is an important tool in proteomics research there are drawbacks of the technique that need further development in order for the approach to be used in clinical laboratories. One major limitation of MALDI MS is the generally poor reproducibility of ion signal intensities, which negatively impacts the quantitation of peptides and protein by MALDI MS. A considerable amount of research has been performed in an effort to improve the ion signal reproducibility in MALDI MS. However, many of the approaches developed have introduced specific drawbacks with respect to the traditional dried-droplet sample preparation technique, negating many of the advantages of the MALDI MS approach. This project has focused on the development of a novel approach to quantify peptides by MALDI MS while preserving traditional known advantages of the technique. The studies performed show that an approach in which the ion signal base widths are manipulated to match that of a reference ion signal, through adjustments in desorption laser intensity, leads to much higher reproducibility in the integrated ion signal intensities. A standard curve acquired using the constant ion signal base width approach showed lower average RSDs (< 10.00% vs.> 39.00%) and improved R2 values (> 0.9600 vs. < 0.809) as compared to the conventional constant desorption laser intensity approach. Subsequent work also revealed that the peptide hydrophobic / hydrophilic properties influenced the applicability of the quantitation approach to mixtures of peptides. Specifically, the data revealed that peptides with differing hydrophobic / hydrophilic properties appear to co-crystallize with the MALDI matrix differently leading to an inability to use a hydrophobic peptide signal to quantitate a hydrophilic peptide, and vice versa. This latter conclusion was further supported in similar studies performed on the mixture of peptides resulting from tryptic digestion of the protein bovine serum albumin.
24

Mazarin, Michaël. "L'ionisation MALDI [Matrix assisted laser desorption/ionization] de polymères synthétiques en spectrométrie de masse." Aix-Marseille 1, 2008. http://theses.univ-amu.fr.lama.univ-amu.fr/2008AIX11034.pdf.

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La spectrométrie de masse après ionisation/désorption laser assistée par matrice (MALDI) apparaît comme une technique de choix pour la caractérisation structurale des polymères synthétiques. Néanmoins, parce que les processus fondamentaux qui régissent la technique MALDI sont encore mal connus, l’optimisation des conditions expérimentales reste empirique. L’objectif de ces travaux de thèse est d’utiliser conjointement des techniques de spectrométrie de masse et de résonance magnétique nucléaire (RMN) pour rationaliser les méthodologies d'analyse des polymères synthétiques par MALDI. Une première approche consiste à utiliser la RMN diffusionnelle pour pré-évaluer la masse moyenne des polymères, valeur qui sert ensuite de guide pour la préparation des dépôts MALDI et l’interprétation des données spectrales obtenues. Un deuxième axe de recherche s’intéresse à la fragilité des groupements terminaux des macromolécules synthétisées par polymérisation radicalaire contrôlée. Les mécanismes de rupture de ces groupements pendant l’ionisation MALDI ont été élucidés en combinant des expériences de dissociation induite par collision après ionisation electrospray, des expériences de RMN en phase liquide et des calculs théoriques. Il ressort de cette étude que seule la protonation du groupement fragile permet la production d’ions oligomères intacts. A cet effet, une préparation sans solvant des dépôts MALDI a été développée pour promouvoir la protonation des macromolécules étudiées. Son efficacité reste néanmoins limitée aux polymères de faible taille. Enfin, le potentiel de la RMN du solide pour caractériser la microstructure des dépôts MALDI a été évalué
Matrix assisted laser desorption/ionization (MALDI) mass spectrometry is a key technique for synthetic polymer structural characterization. Nevertheless, because fundamental process of MALDI is still not fully understood, no standard protocol is available and experimental conditions are empirically optimized. The aim of this PhD work is to combine mass spectrometric techniques with nuclear magnetic resonance (NMR) spectroscopies to develop rationalized MALDI methodologies for structural studies of synthetic polymers. A first approach consists of using diffusion NMR for a rapid evaluation of polymer average mass, to be further used as a guideline in MALDI sample preparation and spectral data interpretation. A second axis deals with fragile end-groups of macromolecules synthesized via controlled radical polymerization reactions. Combining collision-induced dissociation of electrosprayed oligomers with liquid state NMR and theoretical calculations allowed the elucidation of mechanisms involved in the bond cleavage which is observed to occur within such end-groups during the MALDI process. This study shows that protonation of the fragile termination is the main way to allow intact oligomer ions to be produced. A solvent-free MALDI sample preparation was thus developed to promote macromolecule protonation but its efficiency was shown to be limited to the case of small polymers. Finally, the potential of solid state NMR to characterize the microstructure of MALDI sample was evaluated
25

Erb, William Joseph Owens Kevin G. "Exploration of the fundamentals of matrix assisted laser desorption/ionization time-of- flight mass spectrometry /." Philadelphia, Pa. : Drexel University, 2007. http://hdl.handle.net/1860/1765.

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26

Tang, Ho-wai, and 鄧浩維. "Studies on surface-assisted laser desorption/ionization and its analytical application in imaging mass spectrometry." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47145559.

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Surface-Assisted Laser Desorption/Ionization Mass Spectrometry (SALDI-MS) is an analytical technique enabling direct chemical analysis of solid samples. Analytes could be desorbed/ionized upon nitrogen laser irradiation from a SALDI substrate-coated sample, then analyzed by MS. The substrate is involved in the transfer of laser energy to the analytes, and eventually assists the desorption/ionization of analytes. The analytical performance of SALDI-MS, such as detection sensitivity, is dependent on different parameters of the substrate, such as size, morphology and form. In this thesis, the effects of several substrate parameters on the SALDI process were investigated. SALDI-MS based Imaging Mass Spectrometry (IMS) method was also developed using efficient SALDI substrate identified in the fundamental studies. IMS is a chemical-specific mapping technique which allows parallel mapping of multiple analytes in solid samples. The desorption mechanism of SALDI is investigated using two groups of substrate, the carbon allotropes and the noble metal nanoparticles. Ion desorption efficiency and internal energy transfer were probed and correlated in carbon-based SALDI. It was found that the ion desorption efficiency and internal energy transfer was in opposite order. Substrate that transferred more internal energy to ions did not show higher ion desorption efficiency. This result could not be explained by the Thermal Desorption model which was a generally believed mechanism of the SALDI desorption process. A non-thermal model, the Phase Transition model is proposed to account for the SALDI desorption process. The Phase Transition model suggests that the substrate is melted/ restructured upon laser irradiation, and this will assist ion desorption. The Phase Transition model is supported by the morphological change of carbon substrates after SALDI and high initial velocity of ions desorbed by carbon-based SALDI (> 1,000 ms-1). SALDI-MS is useful for small molecule analysis due to the relatively clean background in the low mass region. SALDI-IMS is developed and applied to the imaging of spatial distribution of small molecules in forensic and biological samples. Gold nanoparticles (AuNPs) was selected as the substrate from several other noble metal NPs. A solvent-free method, argon ion sputtering, was employed for coating AuNPs on sample surface prior to SALDI-IMS analysis. Fine details of the samples, such as the fine pattern of latent fingerprints and handwriting on questioned documents can be preserved and imaged reliably by avoiding the use of solvent. Fatty acids, drugs and ink components can be imaged in forensic samples including latent fingerprints, banknotes and checks. The solvent-free SALDI-IMS method was also applied to image the distribution of metabolites in intact animal tissues. Spatial distributions of neurotransmitters, nucleobases and fatty acids can be imaged from mouse brain and tumor tissue sections.
published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy
27

Fiorentino, Michael Armond. "Immediate observation of matrix assisted laser desorption ionization products in a Fourier transform mass spectrometer /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004264.

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28

Moyer, Susanne Catharine. "Phosphotyrosine peptide fragmentation by atmospheric pressure matrix-assisted laser desorption/ionization ion trap mass spectrometry." Available to US Hopkins community, 2002. http://wwwlib.umi.com/dissertations/dlnow/3080729.

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29

An, Hyun Joo. "Characterization of protein-bound oligosaccharides using matrix-assisted laser desorption/ionization Fourier transform mass spectrometry /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.

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30

Stumpo, Katherine Anne. "Size-selected 2, 5, and 10 nm gold nanoparticles for laser desorption/ionization mass spectrometry." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3127.

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31

Smith, Donna M. "Matrix Assisted Laser Desorption Ionization Quadrupole Time-of-Flight Mass Spectrometry of Poly(2-Vinylpyridine)." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1110337309.

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32

Watson, R. Craig Jr. "Laser-Ionization Time-of-Flight Mass Spectrometry of High Molecular Mass Inorganic Complexes." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/35554.

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Laser-Ionization Time-of-Flight Mass Spectrometry (LI-TOF-MS) is a sophisticated tool for the molecular-weight determination and structural characterization of a variety of molecules. Advances in instrumentation and ionization methods have recently expanded its role in the analysis of high-mass analytes. Large multimetallic complexes, which are efficient solar-energy converters, rely heavily on their chemical structure for optimum operation. Molecular mass determinations of these multimetallic complexes have been problematic due to their lability and high molecular weights.

This thesis describes the characterization of a LI-TOF-MS instrument and confirmation of theoretical time-of-flight mass-separation principles. Several test cases demonstrate the instrument's proper operation and calibration for a wide mass range of analytes. Mass spectral results of three organometallic compounds: i. [Ir(dpp)2Cl2](PF6), ii. {[(bpy)2Ru(dpp)]2IrCl2}(PF6)5, and iii. {[(bpy)2Ru(dpp)]2RuCl2}(PF6)5 under a variety of laser ionization and sample preparation conditions are compared. A complete structural characterization of the monometallic complex, [Ir(dpp)2Cl2](PF6), is presented. The two trimetallic analytes fragmented easily, but significant components of the molecules are successfully identified. After optimizing the ionization and analytical procedure, LI-TOF-MS proved useful in the analysis of high molecular mass metal complexes.
Master of Science

33

Hongming, Guo. "IMPROVING MATRIX DEPOSITION FOR SURFACE LAYER MATRIX-ASSISTED LASER DESORPTION/IONIZATION TIME-OF-FLIGHT MASS SPECTROMETRY IMAGING (SL-MALDI-TOF MSI)." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron155654549756264.

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34

Hoteling, Andrew J. "MALD/I TOF PSD and CID : understanding precision, resolution, and mass accuracy and MALD/I TOFMS : investigation of discrimination issues related to solubility /." Philadelphia, Pa. : Drexel University, 2004. http://dspace.library.drexel.edu/handle/1860/318.

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35

Zhang, Jinhua. "Characterization and structural elucidation of oligosaccharides by matrix-assisted laser desorption/ionization Fourier transform mass spectrometry /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.

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36

SUH, MOO-JIN. "MATRIX-ASSISTED LASER DESORPTION/IONIZATION TIME-OF-FLIGHT MASS SPECTROMETRY OF BACTERIAL RIBOSOMAL PROTEINS AND RIBOSOMES." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1106583486.

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37

Ochoa, Mariela L. "Forensic and Proteomic Applications of Thermal Desorption Ion Mobility Spectrometry and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry." Ohio University / OhioLINK, 2005. http://www.ohiolink.edu/etd/view.cgi?ohiou1113585811.

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38

Krutchinsky, Andrew. "A collisional damping interface for a time-of-flight mass spectrometer with both electrospray ionization and matrix assisted laser desorption ionization." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0009/NQ31999.pdf.

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39

Yao, Mengmeng. "Determining Polymer Blend Surface Concentration Using Surface Layer Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (SL-MALDI-TOF MS)." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1407941345.

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40

Hill, Jacob A. Hill. "SURFACE LAYER MATRIX-ASSISTED LASER DESORPTION IONIZATION TIME OF FLIGHT MASS SPECTROMETRY (SL-MALDI-TOF MS) ANALYSIS OF POLYMER BLEND SURFACE COMPOSITION." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1514479406062149.

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41

Chen, Yanfeng. "Analysis of Biological Molecules Using Stimulated Desorption Photoionization Mass Spectrometry." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14620.

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Surface-assisted laser desorption/ionization mass spectrometry (SALDI MS) is a novel technique for direct analysis of organic and biological molecules. Amino acids, dipeptides, and organoselenium compounds were successfully detected by SALDI on carbon and silicon surfaces. Surface effects, solvent effects, temperature effects and pH effects were studied. A possible mechanism of SALDI is proposed based on observed results. In general, stimulated desorption results in neutral yields that are much larger than ion yields. Thus, we have exploited and further developed laser desorption single photon ionization mass spectrometry (LD/SPI MS) as a means of examining biomolecules. The experimental results clearly demonstrate that LD/SPI MS is a very useful and fast analysis method with uniform selectivity and high sensitivity. Selenium (Se) is an essential ultra-trace element in the human body. In efforts to obtain more useful information of selenium metabolites in human urine, mass determination of unknown organoselenium compounds in biological matrices using SALDI MS was investigated. In another approach, several selenium metabolites in human urine were successfully detected by LD/SPI MS. A HPLC-MS/MS method was also developed for a quantitative case study of selenium metabolites in human urine after ingestion of selenomethionine. Low-energy electrons (LEE, 3-20 eV) have been shown to induce single and double strand breaks (SSB and DSB) in plasmid DNA. To understand the genotoxic effects due to secondary species of high-energy radiation, we investigate the role of transient negative ions and the specificity in LEE-DNA damage by examining the neutral product yields using low electron stimulated dissociation SPI MS. The neutral yields as a function of incident electron energy are also correlated with the SSBs and DSBs measured using post-irradiation gel electrophoresis. The results provide further insight concerning the mechanisms of LEE-induced damage to DNA. Overall, this research provided an in-depth understanding of non-thermal surface processes and the development of new mass spectrometric techniques for the analysis of biomolecules.
42

Robins, Chad LaJuan. "Nonpolar matrices for matrix assisted laser desportion ionization - time of flight - mass spectrometry." Cincinnati, Ohio : University of Cincinnati, 2005. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1115293526.

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Thesis (Ph. D.)--University of Cincinnati, 2005.
Title from electronic thesis title page (viewed May 18, 2006). Includes abstract. Keywords: Matrix Assisted Laser Desorption/Ionization Mass Spectrometry; MALDI; Nonpolar Matrices; Charge-Transfer Ionization; Crude Oil; Mass Spectrometry. Includes bibliographical references.
43

Siricord, Cornelia Charito. "Detection of Phytophthora species by MALDI-TOF mass spectrometry." Siricord, Cornelia Charito (2005) Detection of Phytophthora species by MALDI-TOF mass spectrometry. PhD thesis, Murdoch University, 2005. http://researchrepository.murdoch.edu.au/314/.

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Phytophthora diseases have caused worldwide economic, social and environmental impacts for decades. Once their presence is confirmed, they are difficult to eradicate. To reduce and manage the damage inflicted by the pathogen, fast and reliable disease management protocols are required. Tests that enable the rapid and reliable identification of the pathogen assist greatly in disease management. Phytophthora species are traditionally not only detected by baiting but also by plating of symptomatic tissue on selective media. Species can be identified by the characteristics of the mycelium growing out of the bait. However, the method is low throughput, labour intensive, and prone to false negatives. An alternative approach would be to detect the pathogen by the presence of its DNA. This involves amplification of the pathogen DNA using Polymerase Chain Reaction (PCR) and detection of the amplification product. Detection is usually by agarose gel electrophoresis. However, this is also a labour intensive process involving pouring, loading, running, and staining of the gels. The aim of this thesis is to explore the use of Matrix Assisted Laser Desorption/ Ionisation Time-of-Flight (MALDI-TOF) mass spectrometry for detection of PCR products. This procedure enables the analysis of large numbers of samples within a very short time-frame as the average time for analysis of each sample is in the order of milliseconds. The assay involves annealing an extension (genotyping) primer to the PCR product and its extension by a single nucleotide. The nature of the nucleotide added differentiates species as does the site to which the primer anneals. Multiple extension (genotyping) primers can be used together in a single reaction for detection of multiple species. In this project four genotyping primers (GPs) were designed from the ITS regions of Phytophthora palmivora, Phytophthora cinnamomi, Phytophthora citricola, and Phytophthora cambivora. The extension primers were tested for their specificity on the DNA of the target species. The four primers designed were specific for their intended targets except for GPpalm3 which in addition to being extended by ddT when tested with DNA from P. palmivora, was also extended by ddC when tested with DNA from other species of Phytophthora or Pythium. These primers were also tested for their ability to detect multiple Phytophthora species in a single reaction (multiplexing). Mixtures of primers were added to mixed DNA templates and the primer extension reaction carried out. The primers were designed so that their masses were sufficiently different for them to be identified from a mixture. Six replicates were analysed for each reaction. In general only about 1-3 of the six replicates gave a positive reaction. This indicates that there may be some interference between primers, or that the presence of all four nucleotides interfered with the primer extension reaction. Increasing either the amount of enzyme, the amount of nucleotides or both did not improve the results. The sensitivity of detection was tested by the addition of different amounts of mycelium to soil. The detection sensitivity depended on the primer pair used for PCR amplification. The ITS1/2 primer pair was more sensitive than the ITS1/4 pair. The limit of detection was 1 mcg mycelium g soil-1. However using nested PCR, levels of sensitivity comparable to those obtained using the ITS1/2 primer pair could be achieved. Primers to other regions of the genome such as the beta cinnamomin elicitin gene gave very low levels of sensitivity compared to the ITS primers. In comparison with DNA detection we found that the limit of detection using baiting was 4 mcg mycelium g soil-1. Results below this limit were unreliable. The method suffered from the additional disadvantage that it took a long time in comparison to DNA detection. DNA detection methods do not distinguish between living and dead organisms in the soil. However it can be hypothesised that DNA is unlikely to persist for any significant length of time in soil. To test this, we added plasmid DNA to soil and tested the persistence of this DNA using a variety of methods such as precipitation of labelled DNA, southern blotting and PCR amplification. It was found that in general, in soils from different ecosystems, the bulk of the DNA was undetectable after 24 hours. The rate of DNA breakdown differed with the soil type. In some soils, the added DNA was not detected even after 2 hours, whereas in others it could be observed after 10 hours. The detection depended on the method. Southern blotting showed that although DNA could be observed at 10 hours, by 24 hours it was completely degraded. In contrast a PCR product could be obtained from the soil extracts up to 24 hours. In a separate experiment, plasmid DNA was detectable over a 24 hour incubation period in 5 soil samples from 5 different sites. The results suggest that DNA is degraded rapidly in soil and is unlikely to persist longer than 24 hours. The results in this thesis demonstrate that MALDI-TOF MS is a suitable alternative to agarose gel electrophoresis for analysis of PCR products. The technique is rapid, differentiates species from mixtures, is high-throughput and amenable to automation. Implementation will require further research to automate the primer extension assay to reduce the sensitivity to impurities in the DNA and to design parameters for sampling asymptomatic material.
44

Holcomb, April M. Owens Kevin G. "Investigation into the ionization mechanism occurring in matrix assisted laser desorption ionization and factors affecting ion flight time in MALDI time-of-flight mass spectrometry /." Philadelphia, Pa. : Drexel University, 2009. http://hdl.handle.net/1860/3161.

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45

Emanuele, Vincent A. II. "Advancements in high throughput protein profiling using surface enhanced laser desorption/ionization time of flight mass spectrometry." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37287.

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Surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI)is one of several proteomics technologies that can be used in biomarker discovery studies. Such studies often have the goal of finding protein markers that predict early onset of cancers such as cervical cancer. The reproducibility of SELDI has been shown to be an issue in the literature. There are numerous sources of error in a SELDI experiment starting with sample collection from patients to the signal processing steps used to estimate the protein mass and abundance values present in a sample. This dissertation is concerned with all aspects of signal processing related to SELDI's use in biomarker discovery projects. In chapter 2, we perform a comprehensive study of the most popular preprocessing algorithms available. Next, in chapter 3, we study the basic statistics of SELDI data acquisition. From here, we propose a quadratic variance measurement model for buffer+matrix only spectra. This model leads us to develop a modified Antoniadis-Sapatinas wavelet denoising algorithm that demonstrates superior performance when compared to MassSpecWavelet, one of the leading techniques for preprocessing SELDI data. In chapter 4, we show that the quadratic variance model 1) extends to real pooled cervical mucus QC data from a clinical study, 2) predicts behavior and reproducibility of peak heights, and 3) finds four times as many reproducible peaks as the vendor-supplied preprocessing programs. The quadratic variance measurement model for SELDI data is fundamental and promises to lead to improved techniques for analyzing the data from clinical studies using this instrument.
46

Abell, Darcy Cameron. "Analysis of potato glycoalkaloids by ELISA and matrix assisted laser desorption/ionization time-of-flight mass spectroscopy /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq22940.pdf.

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47

Wu, Li-Chieh, and 吳俐節. "Development of thin layer chromatography/electrospray laser desorption ionization mass spectrometry and its applications." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/13603098618638216212.

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48

Liou, Jhao-Yan, and 劉昭延. "Development and Applications of Thermo Desorption and Laser Desorption Electrospray Ionization Mass Spectrometry." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/q8kt9r.

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碩士
國立中山大學
化學系研究所
107
With the rapid development of ambient mass spectrometry (AMS), different functions of ambient ionization have also been reported. Based on the different sampling/desorption methods, AMS can be classified as thermal desorption, laser desorption, and gas stream methods. Thermal desorption was used to characterize volatile or semi-volatile compounds in liquid or solid samples, while laser desorption was applied to detect non-volatile samples. The method of gas stream was developed to determine volatile and thermally unstable compounds in solution. The purpose of this thesis is to develop a new ambient ionization technique called thermal desorption and laser desorption electrospray ionization mass spectrometry (LD+TD-ESI/MS), which is capable of analyzing polymer materials and alkaloids in plants. Thermal desorption and laser desorption electrospray ionization mass spectrometry comprised a continuous infrared laser device, a copper tube heating device, a temperature controlled nitrogen stream device and an electrospray ionization device. Since the ion source provided high power for laser desorption, thermally stable to be heated, and temperature-controlled auxiliary to transfer analytes, the system can be simultaneously detected non-volatile and volatile analytes. Herein, the ionization mechanism will be explained in detail and performances related to instrumentation will also be optimized, including its repeatability, reproducibility, sensitivity, and robust procedure. In the second part, LD+TD-ESI/MS was used for direct analysis of the polymer materials. Firstly, a complete database of polymer material was established. Various plastic products commonly used in daily life were directly analyzed. The resultant polymers, in addition to additives of the samples, were rapidly characterized. In addition, LD+TD-ESI/MS can also detect alkaloids. In potato with sprouts, the signals of both α-chaconine and α-solanine can be detected. According to the previous literature, potatoes contain toxic compounds known as glycoalkaloids, of which the most prevalent are α-chaconine and α-solanine. It is pointed out that α-chaconine and α-solanine account for more than 95% of the total amount of glycoalkaloids. Additionally, they cann’t be decomposed by heating. Once the excessive intake of glycoalkaloids is in danger of acute poisoning. Thus, the rapid identification of glycoalkaloids will help prevent the recurrence of such poisoning tragedies.
49

Hong, Hui Min, and 洪惠敏. "The study of metal complex salts in laser desorption ionization." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/25823194337932205675.

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50

Ovchinnikova, Olga Sergeevna. "Spatially Resolved Laser and Thermal Desorption/Ionization Coupled with Mass Spectrometry." 2011. http://trace.tennessee.edu/utk_graddiss/1112.

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The work discussed in this dissertation is aimed at creating novel approaches to chemical imaging that ultimately allow for submicron resolution. This goal has been approached from two direction using laser based desorption and coupling it with an AFM using apertureless tip-enhanced laser ablation/ionization. The second direction was through the development a new approach to thermal desorption based mass spectrometry experiments by using a proximal probe to spatially desorb the surface and ionizing the plume of neutrals using a secondary ionization source at atmospheric pressure. The thermal desorption approach allows for the easy scaling of the technique all the way from the millimeter to the nanometer regime. In the nanometer regime an AFM platform with silicon based heating AFM probes is used to locally desorb material from nanometer sized craters. The final work in this thesis focused on trying to improve laser based desorption through a secondary ionization of the neutrals plume by capturing the laser desorption plume into a liquid and then electrospaying the solution into a MS. The added benefit of being able to capture the desorption plume into a liquid is the ability to carry out post sampling processing of the captured analyte via high performance liquid chromatography. The ability to clean up a sample via HPLC also allow for the detection of isobaric compounds as well as trace level materials which otherwise would be obscured by matrix effects in complicated sample matrixes like tissues. This application of laser desorption with a secondary ionization by capture into a liquid could be envisioned to be applied to AFM based laser desorption techniques where boosting the ionization efficiency is crucial for signal detection.

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